An extremist described as the Animal Liberation Front's leading bomber was jailed for 12 years and placed on licence for life yesterday after a bombing campaign against people he believed were associated with animal research.

In what police described as a "devastating blow" to animal rights extremism, Donald Currie, 40, was told he would be subject to parole conditions for the rest of his life, even after his release from prison, such was the danger to the public.

Currie, an unemployed former psychiatric nurse of no fixed abode, planted home-made bombs outside the homes of a senior pharmaceutical company executive and the director of a courier firm, one of which ignited and could have caused serious injury, Reading crown court was told. Both companies have indirect links to Huntingdon Life Sciences, Britain's biggest drug-testing laboratory, which has been the target of a sustained campaign by activists opposed to animal testing. At least six separate but similar offences involving incendiary devices are being investigated across seven police forces.

In the first of two attacks for which he was convicted, Currie targeted the home of Paul Blackburn, a senior executive for GlaxoSmithKline, in Beaconsfield, Buckinghamshire, in September last year, placing a device made of matches, cigarettes and a bottle of white spirit on the doorstep.

It exploded in what firefighters described as a "large fireball" shortly after being discovered by Mr Blackburn's adult daughter at 11pm. The businessman was away from home, but his wife and another daughter, aged eight, were asleep inside at the time. The attack on the family followed years of phone calls and intimidation at their home.

On March 26 this year Currie attempted to bomb the car of Caroline Brooks, the sales and marketing manager of a firm called PDP Couriers, which carries out work on behalf of a subsidiary of HLS. Her family had been the subject of a "virulent campaign of harassment and intimidation", the court heard, in which her cars had been damaged and she had been sent violently abusive letters. One posting on a website which claims to speak for the ALF read: "You profit from animal testing. You are a sick, evil pervert. You filthy, animal killing scum."

On the evening of the attack, in Caversham, Reading, Ms Brooks and her partner disturbed Currie planting a device under one of their cars. He fled, and a second bomb was found abandoned in a hedge. The couple's two children, aged 11 and 14, were in the house at the time. Currie was arrested at the end of the family's street, close to a bicycle on which he planned to escape. He was carrying a fire lighter and cigarette lighter and wearing a mask.

Sentencing Currie, Judge Zoe Smith said: "You are entitled to hold strong views and to oppose vivisection by protesting peacefully. But what you cannot do is enforce your views with violence."

His actions, she said, had devastated his victims and left Ms Brooks "living in a state of fear". "I am of the opinion that you pose a significant risk to the public, and I am required by law to pass a sentence for public protection."

Currie has previous convictions for criminal damage, assault, threatening behaviour and destroying badger traps. His wife Karen, 38, is also an activist.

Det Supt George Turner, who led the police investigation, said Currie's conviction "will have a significant effect on the illegal activities of animal rights extremists in the UK".

The court's public gallery was packed with supporters who applauded Currie and shouted encouragement. Among them was Mel Broughton, who was jailed for four years in 1997 for conspiring to pursue a similar bombing campaign and who now leads the campaign against the building of an animal research laboratory in Oxford, another key target of animal rights activists.

Backstory

New legislation and jailings have halved the number of attacks by animal rights activists on homes in the first six months of 2006, compared with last year. In September, Joseph Harris, 26, a specialist in pancreatic cancer, was jailed for three years for vandalising three firms with links to Huntingdon Life Sciences. In May, three people were jailed for 12 years for stealing the remains of Gladys Hammond from her grave. Oxford University also won an order banning campaigners from threatening contractors at the site of a new animal testing lab.